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I've been following the guys down at Reaction Engines and their SABRE engine concept for a few years. These are the same guys who came up with the HOTOL concept at Rolls Royce in the 1980's. No word on what they'd use for thermal protection on re-entry but they're a clever bunch and if I came into a billion pounds I'd shove a fair chunk of it at these guys to build me a fleet of spaceships to rule the world;-)

If they could get government funding we could lead the world in launch capabilities. However, what would probably happen is that we'd end up handing it over the the USA as our leaders are too short sighted and too cheap to fund anything truly visionary or world beating.

At which point our leaders would promptly turn it over to venture capitalists, who would immediately strip the company of any and all value and sell what's left off for their own personal profit.

It's true. That's why promising companies started out by rich people venturing their capital have all been picked clean, and are now gone. I was so hoping that Space-X, Virgin, Orbital Sciences, and others would survive past their first couple of years, but the Eeeeevil Rich People just sold 'em off to buy gold plated spinning hubcaps for the Bentleys they use to drive over the poor people they use as speedbumps on the private estates where they hunt endangered cheetahs for sport.

What is par for the course? The dismantling of companies like Virgin by evil US investors?

The meme I'm referring to is that nice popular one, where venture investors don't build anything, don't see the money they risk ever put to good use, and that nothing good comes from them pushing small or dying companies into a healthy, viable condition. That's pure BS, on the face of it. But that image, that meme, is trotted around as if it were true - all because people who don't have money to invest and who don't

I did read somewhere (i thought it was on their website but can't find it now) that they wouldn't need ceramic tiles like the shuttle due to the high drag to weight ratio during re-entry. I assumed that this just meant they would be trying to slow down as much as possible before the heat built up too much.
On the website it currently suggests the will use excess hydrogen to cool to the surfaces and dump in over board.
If i find the source of the high drag to weight ratio i will post it here later

IOn the website it currently suggests the will use excess hydrogen to cool to the surfaces and dump in over board.

They hydrogen will at that point become superheated and immediately react with any oxygen in the rather thin air up there... At least this is what I hope would happen, because it would look awesome on re-entry.

He might be. Reaction Engines doesn't name its investors (or the ones who have pledged much larger sums of money, contingent on technology milestones like this precooler test being completed successfully

I agree, he won't put his brand on something this unready, but he might put his money into it.

Personally, I think SLS is only a stop-gap measure because NASA is too deeply engrained with...ahem...an older generation that won't move outside of a certain comfort zone, so I'm really happy to see something like this. I'm also hoping that they've got enough financial backing to make it a reality. Who knows? Maybe Peter Diamandis, James Cameron, Larry Page, and Eric Schmidt can use this technology to launch the second phase of Planetary Resources' mining operations!

Heh...if you ask me, we should fire everyone in Congress and the Senate, and take the government, especially the Legislative branch, back to the way it was intended, eliminating career politicians
No more Nancy Pelosi, no more John Boehner. We keep our eye on the prize, and we let no one, and I mean no one, get in our way./jay

At high speeds, the Sabre engines must cope with 1,000-degree gases entering their intakes... Reaction Engines' breakthrough is a module containing arrays of extremely fine piping that can extract the heat and plunge the intake gases to minus 140C in just 1/100th of a second.

That is... impressive, to say the very least. It sounds from Wikipedia [wikipedia.org] like they are even using the heat energy to power the turbo compressor (wondering if it was possible to convert the heat to useful energy was one of my first thoughts). I'm curious how efficient the jet is at low speeds, though. Typically, most jet engines work well at either low or high speeds, not both.

These kinds of engines are definitely needed to make space travel cheaper. Much cheaper, potentially, than solid-state rockets.

I would guess they don't worry about efficiency at low speeds, since they don't plan to fly at low speeds for very long. As long as it's not so inefficient that it can't accelerate past the problem into its "comfort zone", of course...

I though the hard part of making a space plane was that reentry is still a burn in problem. There is no way to slowly glide into the atmosphere without having to be fire and melt proof. and those requirements make it hard to build a plane that can take off enter space, re-enter and land.

I'm betting we can make one now that can take off and make it to orbit, it's the coming home part that is the problem.

STS didn't need to have air intakes that hang out in the breeze... that simple difference makes the engineering problems a whole lot more difficult.

I've worked in commercial and government space for nearly 30 years, and one thing I've learned is that most, nay almost every, new launch system idea that sounds promising and brilliant in the concept stage runs aground on shoals of engineering problems with the result of either grossly inflated cost and schedule, or catastrophic failure. Layman frequently underestimate how much of the technology space has been explored and found to be dead ends due to either unsurmountable technical difficulties or simple economics. Incremental materials improvements are the most common route to innovation, but they can only do so much to open up new avenues.

In other words, it's not always possible to identify technical risks early on. The history of launch systems is full of "oh, shits." The cliche "the devil is in the details" may very well have been coined by a rocket scientist.

That said, I wish them luck and good fortune. If there's a way that we haven't yet achieved of bumping up the payload fraction of conventional launch systems, this is it. Hybrid jet/rocket engine approaches are also one place where I believe the introduction of improved materials can be disruptive. REL may have found a new route to orbit, and I hope it works for them.

Interesting stuff; it's nice to hear a voice that actually knows what it's talking about every once in a while.

Layman frequently underestimate how much of the technology space has been explored and found to be dead ends due to either unsurmountable technical difficulties or simple economics.

True, but as I recall, around the turn of the century we were experiencing similar issues with deep sea exploration, albeit regarding the intense pressures of the deep as opposed to the vacuum of space. In less than 100 years, we went from the Beebe and Barton observing jellyfish at nearly 1400 ft depth in their Bathysphere, to a movie director exploring the Challenger Deep (35,000+ ft below sea le

The air intakes are closed on re-entry (and whenever else they aren't being used.) There is a cone shaped 'plug' at the front of each engine that can be used to vary the intake for different speeds/altitudes, or close it altogether.

In other words, a large articulated structure that must be insulated but still function perfectly over an extremely large range of temperatures, pressures, and airspeeds (including some combinations of which we've never made such a thing work - see the recent news about the HTV-2 failure board report). It must operate reliably within strict tolerances both before and after being subjected to the dynamic stresses of launch and the thermal stresses of re-entry, and it must be economically re-usable, re-worka

Bear in mind, this project is a descendent of HOTOL, and thus has about 30 years of work behind it. Contrary to what some people seem to think, its not an few cool rendered movies and an engineering drawing.

Consider, for instance, that part of the motiavtion for beginning Skylon was because HOTOL had insurmountable engineering problems (crappy payload fraction, and a centre of mass whose motion would make the rocket dangerously unstable as its tanks emptied.) This is essentially a iteration of the air-breat

If I remember my readings about this system correctly, the thermal load is expected to be much smaller than the shuttle ever experienced. Since the SABER engines use liquid hydrogen, the tanks are absolutely massive - and on reentry, they're mostly empty. So it's much larger and much lighter than the shuttle. Light, massive objects slow down much, much faster on reentry.

I'm not an engineer, but if the craft (like the one envisioned) is much lighter than the space shuttle, is the re-entry heat still such a huge obstacle? Just spitballing here, but say a low-orbit vehicle just starts 100% throttle at a vector that is 100% opposite to the direction it's travelling: if it's light, it can decelerate rapidly in space, then just fall to earth and use the wings to glide in when it's in thicker atmosphere, right?
Maybe I'm way off here, just curious if that would work.

Deccelerating something from orbital velocity is just as difficult as accelerating it to orbital velocity in the first place, except you've expended all your fuel already. Much easier to use the atmosphere.

The issue isn't necessarily protecting the bulk of the spacecraft, it's protecting those parts that have openings to the outside world. It's easy to design an ablative thermal protection system, or a ceramic-based one, but the tough part is sealing the air inlets, docking ports, etc, etc, etc, such that superheated gasses can't melt the turbine blades or fuel nozzles within the engines. Yeah, you can have moveable doors that would swing open to block the ports, but you've got to make sure they're SEALED, and you've got to make sure that they can open again, reliably, after re-entry, so that you're able to start up your engines on the air cycle and make a safe landing.

There is no way to slowly glide into the atmosphere without having to be fire and melt proof.

Your sentence is twice as long as it ought to be. If you could manage to slowly glide into the atmosphere, you wouldn't need to be fire and melt proof. The problem is, you simply can't slowly glide into the atmosphere to begin with. Among other things, until you enter the atmosphere, you can't glide at all, and you're likely to be coming in at near orbital velocity, and even if you did slow down before hitting the atmosphere, gravity will helpfully~ accelerate you back up to ludicrous speed.

"I'd also think the fancy cooling on the engine they show here is mostly for the turbine operating between mach 2.5 and mach 5 where the compressor blades would start to seriously heat up."

The idea is actually to liquify and store the air as they fly to provide oxidizer for the rocket phase of flight. I think they're freaking nuts, but if they can do it then they are truly gods among engineers.

This is largely due to my ignorance of how space travel actually works, but why can't you descend gradually (or more gradually than we already do)? Wouldn't that reduce the overall maximum heat that the craft is exposed to?

This is largely due to my ignorance of how space travel actually works, but why can't you descend gradually (or more gradually than we already do)? Wouldn't that reduce the overall maximum heat that the craft is exposed to?

It all comes down to available fuel. Spacecraft burn most of their fuel getting into orbit, meaning that they usually have just enough left to drop their orbit into the atmosphere, where aerodynamic drag takes over. To descend gradually, you would need to have just as much (if not more) fuel as required to get into orbit in the first place, since you would have to slow down a LOT more than currently feasible. And after that you would need even more fuel to control your descent rate, since even if you stoppe

A huge parachute in the thin atmosphere to slow down your orbital decent before you hit the thicker air?

Sounds like the trick they used in 2010. While I don't have any figures to spout off as to why it wouldn't work, it does still strike me as being a bad idea. But unfortunately I'm at a loss as to why I think that. My guess is that at the velocities involved, the stresses on the craft would be rather obscene.

I though the hard part of making a space plane was that reentry is still a burn in problem. There is no way to slowly glide into the atmosphere without having to be fire and melt proof.

Strictly speaking, that's not true. The heat happens because the atmosphere is used to slow the spacecraft down from orbital speeds. Its massively cheaper than carrying your own fuel to slow down. If you could slow from 17000mph to 0mph at the same rate you accelerated up from the ground, you'd have dropped most of your speed before the atmosphere got that thick and you'd just fall at terminal velocity.

Not that it helps with this scenario, but if the asteroid miners eventually get hydrogen and oxygen availa

Well, sort of. It's all engine research. And I hope that we'll continue doing research, even if we get a working space plane. There's allways more to learn, new discoveries to be made, system to optimize.

What makes the Skylon concept different is the engine. Instead of a SCRAM-jet air breathing engines they're going for a traditional rocket engine that is fed pressurized air, while in the atmosphere. This is advantageus to the SCRAM-jet and rocket approach, since only a single engine is needed for getting i